1. Field of the Invention
The present invention relates to an ear hook type of hearing aid.
2. Description of the Related Art
A conventional ear hook type of hearing aid comprised an ear hook that was bent so as to fit the ear, an earphone linked to the front end side of this ear hook, and a main body case linked to the rear end side of the ear hook. The main body case is formed in a shape that curves downward in a parabolic shape from a front end portion toward a rear end portion of its own.
A front microphone and a rear microphone were provided inside this main body case. The front microphone was acoustically connected via a front sound conducting path to a front sound hole provided to the front end portion of the outer wall face of this main body case. The rear microphone was acoustically connected via a rear sound conducting path to a rear sound hole provided to a portion of the outer wall face of this main body case that was farther to the rear than the front sound hole.
A battery case that is removable by turning is installed inside the rear end portion of the main body case. On this battery case were formed a first locking protrusion that engaged with the main body case when the battery case was installed inside the main body case, and a pressing protrusion that was opposite a fitting-use first communication terminal provided inside the main body case when the battery ease was installed inside the main body case (see, for example, U.S. Pat. No. 6,088,465).
When this hearing aid is used, first the ear hook is hooked over the top of the ear, and then the earphone is placed against or inserted into the ear canal in this state. Because the main body case is formed in a shape that curves downward in a parabolic shape from a front end portion toward a rear end portion, it was disposed along the rear side of the ear when the hearing aid is used.